[1] Optum, Ann Arbor, MI 48108 USA
[2] GlaxoSmithKline, WorldWide Epidemiol, Res & Dev, Collegeville, PA 19426 USA
[3] GlaxoSmithKline, Clin Dev, Res & Dev, Res Triangle Pk, NC 27709 USA
[4] GlaxoSmithKline, WorldWide Epidemiol, Res & Dev, Res Triangle Pk, NC 27709 USA
[5] Harvard Univ, Brigham & Womens Hosp, Div Pharmacoepidemiol & Pharmacoecon, Dept Med,Med Sch, Boston, MA 02115 USA